Cardiac function management systems are used to treat arrhythmias and other abnormal heart conditions. Such systems generally include cardiac leads, which are implanted in or about the heart, for delivering an electrical pulse to the cardiac muscle, for sensing electrical signals produced in the cardiac muscle, or for both delivering and sensing. The lead typically consists of a flexible conductor, defining a central channel or lumen, surrounded by an insulating tube or sheath extending from an electrode at the distal end to a connector pin at the proximal end.
Cardiac lead placement may be accomplished by introducing the lead through a major blood vessel and advancing a distal end of the lead to a final destination in or near the heart. To facilitate cannulation of the vasculature, it is often helpful to first advance a guiding catheter through the desired vascular path. One difficulty with implanting leads in this fashion is that the cardiac lead has a tendency to become dislodged from its desired location during or after lead implantation. For example, when a clinician withdraws the guiding catheter, the lead may dislodge or otherwise reposition. Until tissue in-growth ultimately fixes the lead at the desired site, cardiac leads may also become dislodged by subsequent physiological activity.
A variety of passive means devices have been secured to cardiac leads to affix the leads at a desired location in a patient's vasculature by exerting a radial force against vein walls. Nonetheless, there is a need in the art for a cardiac lead having a fixation mechanism which effectively affixes the cardiac lead at a desired position in a non-destructive manner, but which also allows the lead to be repositioned within or removed from the patient's vasculature, even after an extended implantation period.